1. Field of the Invention
This invention pertains to improvements in methods and apparatus for the production of filled, edible products, such as doughnuts, particularly products of a hollow-center, ring-like configuration but which can also be of other shapes.
2. Description of the Prior Art
Various types of techniques have been used for injecting into doughnuts a filling material, such as cream or jelly. These devices primarily use some form of extrusion technique for forming the product, then either extrude or inject the filling material into the product while in a yet unformed state and then finally form the product around the filling material. These various techniques have generally involved very elaborate mechanical mechanisms to control and guide the flow of both the filling material and the product material and thus have been expensive to manufacture and difficult to maintain.
One problem in injecting the filling material into edible products that are later cooked, as in a fryer, is that the filling material, during the injecting process, is not adequately sealed from the outside surface of the product, preventing the formation of a good bond between the product material at the surface of the product and impairing the quality and appearance of the final product.
Various techniques known to Applicant for filling doughnutlike products are described in the following U.S. Pat. Nos. 3,452,687; 3,362,355; 3,196,810; 2,982,231; 1,933,557.